Close Contact Transillumination Light Guides Surgeon to Vaginal Point Aa: Pharus Method for Robot-Assisted Sacrocolpopexy

Introduction: In robot-assisted sacrocolpopexy (RSC) for patients with cystocele, accurate identification of the vaginal point Aa from the serosal side is crucial for surgical mesh placement in the appropriate position. We developed a novel Pharus method for exactly locating the point Aa for RSC.

Methods: In the Pharus method, the tip of a rigid endoscope was placed directly on the vaginal point Aa. In a preliminary experiment, we observed LED lights with different wavelengths of 450-870 nm using the Firefly imaging system to evaluate which wavelengths of light were captured by the Firefly mode. In a clinical study, the Pharus method was employed in four patients with Stage II or more advanced cystocele undergoing RSC. For comparison, a near-infrared fluorescence method by indocyanine green (ICG) tattooing at the point Aa was also performed. The visibility of each method was evaluated under Firefly-mode imaging.

Results: In the preliminary experiment, visible LED lights with wavelengths ≤ 720 nm, and near-infrared LED lights with wavelengths ≥ 830 nm were detected by the Firefly mode. In RSC using the Pharus method, the point Aa of each patient was clearly highlighted as a green spot from the serosal side by the endoscopic white light penetrating the vaginal wall with a thickness of 3.3-4.6 mm. Compared with the ICG tattooing method, the Pharus method showed superior visibility in all patients.

Conclusion: The transillumination light effectively guided the surgeon to the vaginal point Aa, which can be likened to the Latin word "pharus," meaning lighthouse.